The invention relates to a treatment step made during slaughter of fresh meat and more particularly to treating pork, beef, veal, mutton, lamb and goat carcasses with a solution of alkali metal orthophosphate to remove, retard or reduce bacterial contamination and/or growth without causing substantial organoleptic depreciation of the meat.
Red meat, during and after slaughter, may contain or become contaminated with certain undesirable bacteria such as salmonella, campylobacter, listeria, spoilage bacteria, and the like. The red meat is processed by removing the hide, eviscerating, cooling and cutting into larger cuts for fresh, cured meat or boxed meat. The fresh red meat obtained after evisceration is chilled by hanging the sides of red meat at a temperature usually below 10.degree. C. Beef is hung for a considerable period to allow natural enzymes to tenderize the beef. Pork is simply cooled. For certain primal cuts, such as ham, bacon, corned beef and pastrami the cuts are cured by chilling below 10.degree. C. followed by injection of a solution containing salt, nitrite and/or nitrate, sweetener, cure accelerator, one or more polyphosphates, spices and flavorings. The meat is prepared to 105% to 130% of its weight with curing solution. Boxed meat is cut into primal cuts after chilling, vacuum packaged and boxed.
As disclosed in U.S. Pat. No. 3,782,975 to Zyss, primal cuts of red meat are maintained between 32.degree.-42.degree. F. (for about 3 to 5 days). During that period, the sodium nitrite reacts with the myoglobin of the meat to form nitrosomyoglobin which insures good color to the meat. The addition of the curing solution to the primal cuts imparts improved texture, tenderness, flavor and color that would be lacking if the curing brine was not added to the meat. Zyss teaches that for people with a sodium problem, a pumping solution of potassium salts including potassium orthophosphates could be employed.
A second patent to Zyss, U.S. Pat. No. 3,775,543, suggests the addition of phosphate compositions including potassium orthophosphates to processed meats as a binding agent in from 0.2 to 2.0% by weight of the mix. Zyss clearly avoids alkaline pH since he indicated that alkaline pH decreases the meat's shelf life. Zyss neutralizes with acid to pH 6.4 to 6.8. In example II, Zyss prepares a bologna product using about 1% tripotassium orthophosphate. Surprisingly, we have found that surface orthophosphate treatment increased shelf life.
Ueno, et al. U.S. Pat. No. 4,592,892, uses ethanol to sterilize certain food and processing machinery and may employ a carbonate and/or trialkali orthophosphate combined with the ethanol to enhance the ethanol's effectiveness.
Several patents to Swartz, U.S. Pat. Nos. 3,493,392, 3,620,767, and Canadian Patent No. 847,280, use phosphates including sodium orthophosphate as a processing aid for fish.
Bynagte, U.S. Pat. No. 3,705,040, uses phosphates to help remove shrimp from their shells. Sodium orthophosphate at 2-15% with other ingredients can be employed.
Cheng, U.S. Pat. No. 4,683,139, teaches a process for prepackaged fresh meat at retail wherein the shelf life of the meat is increased by treatment with an aqueous solution of an alkali metal salt of certain phosphate compounds, a reducing compound such as ascorbic acid and a sequestering or chelating agent such as citric acid. The phosphate can be an orthophosphate, pyrophosphates, tripolyphosphates and hexametaphosphates. Meat pH is below neutral.
Szczesniak et al., U.S. Pat. No. 4,075,357, teaches salt combined with a secondary salt selected from alkali metal salts of organic acids and trisodium orthophosphate, polyphosphate, metaphosphate and ultraphosphate. Citrates are preferably combined with sodium chloride. These mixtures are used to control water activity in intermediate moisture cooked food.
Kohl, et al., U.S. Pat. No. 3,681,091, teaches treating foods including fish fillet with 10% solutions of medium chain length polyphosphates.
Freund, et al., U.S. Pat. No. 2,957,770, teaches improving the properties of meat with a casein composition which can include inorganic orthophosphates such as disodium hydrogen orthophosphate.
Many treatment systems for poultry have been suggested. It has been reported that the thermal death rate of salmonellae can be increased during scalding by elevating the pH of the scald water to pH 9.0.+-.0.2. Agents such as sodium hydroxide, potassium hydroxide, sodium carbonate, and trisodium phosphate have been reported as effective pH adjusting agents for use in increasing the thermal death rate of the bacteria. Trisodium phosphate was reported as least effective in increasing the death rate. See "The Effect on pH Adjustment on the Microbiology of Chicken Scald-tank Water With Particular Reference to the Death Rate of Salmonellae", T. J. Humphrey, et al., Journal of Applied Bacteriology 1981, 51, pp. 517-527.
T. J. Humphrey, et al. have also reviewed the pH effect of scald water on Salmonella on chicken skin. See "The Influence of Scald Water pH on the Death Rates of Salmonella typhimurium and Other Bacteria Attached to Chicken Skin", Journal of Applied Bacteriology 1984, 57 (2), pp. 355-359. Scald water adjusted to pH 9.+-.0.2 as in the 1981 paper can help to reduce external and internal cross-contamination of carcasses by salmonellas.
"Phosphate and Heat Treatments to Control Salmonella and Reduce Spoilage and Rancidity on Broiler Carcasses", J. E. Thompson, et al., Poultry Science, 1979, 58, 139-143 teach kenaphosphate a blend of 90% sodium tripolyphosphate and 10% sodium hexametaphosphate did not consistently or effectively effect either salmonella survival or total bacterial count.
Attempts have made to pasteurize poultry meat by treating the meat with a solution containing agents such as lactic acid, acetic acid, sodium carbonate, sodium borate, sodium chloride, potassium hydroxide, chlorine and EDTA. All 6 treatments, except sodium borate, sodium chloride, and sodium carbonate, reduced the visual acceptability of the meat. Chlorine failed to destroy bacteria on the surface of the poultry but would be expected to control salmonellae in water. See Chemical Pasteurization of Poultry Meat, J. S. Teotia, Disseration Abstracts Int'l. B., 1974, 34(a), 4142.
It is known that the shelf life of chicken carcasses can be increased 1 to 2 days by chilling the poultry in a solution of 6% sodium tripolyphosphate/0.7% tetrasodium pyrophosphate (Kena - available from Rhone-Poulenc, Inc., Food Ingredients Division). See The Antimicrobial Effect of Phosphate With Particular Reference To Food Products, L. L. Hargreaves, et al., The British Food Manufacturing Industries Research Association, Scientific and Technical Surveys, No. 76, April, 1972, Pages 1-20 at Page 12. Many patents and articles suggest the use of polyphosphates in preserving meat and fish products.
In addition, it is also stated in the Hargreaves reference at page 7 that G. Pacheco and V. M. Dias in an article entitled Bacteriolytic Action of Phosphates, Mems Institute Oswaldo Cruz, 52 (2) ppg. 405-414, reported on the bacteriolytic action of solutions of monosodium, disodium, trisodium and dipotassium orthophosphates on dead and living cells of Salmonella typhosa, Escherichia coli and Staphylococcus aureus. Trisodium phosphate dodecahydrate is stated to have the greatest lytic action. The reference does not relate to treating meat or fish.
British patent 935,413 teaches treating raw poultry in the chill tank with a non-cyclic polyphosphate. It is taught that this method provides increased preservation of the poultry flesh by decreasing exudate and thereby decreasing spread of bacteria.
Trisodium phosphate has also been found to be effective in inhibiting the growth of blue mold in cuts and bruises in fruit by treating the broken surface with the solution of trisodium phosphate (U.S. Pat. No. 1,774,310).
Trisodium orthophosphate is also a known and widely used anticaking agent (see U.S. Pat. No. 2,770,548).